A Chinese man has pleaded guilty in a “years-long” conspiracy to hack into U.S. networks to steal sensitive information, including data on the C-17 cargo plane and fighter jet aircraft, the Justice Department announced Wednesday.

Su Bin, also known as Stephen Su and Stephen Subin, 50, a citizen and resident of the People’s Republic of China, pleaded guilty to the crime in the United States District Court for the Central District of California, according to a press release from the department.

A China-based businessman who worked in the aviation and aerospace fields, Su is accused of playing a role “in the criminal conspiracy to steal military technical data, including data relating to the C-17 strategic transport aircraft and certain fighter jets produced for the U.S. military,” it states.

The release didn’t specify which type of fighter aircraft, though American officials have long pointed to similarities in China’s latest designs as evidence of its successful theft of technical data from the U.S.

During a congressional hearing last fall, Sen. Joe Manchin, a Democrat from West Virginia, noted that China’s Chengdu J-20 twin-engine stealth fighter resembles the F-22 Raptor made by Lockheed Martin Corp., while the Shenyang J-31 twin-engine multi-role fighter resembles the F-35 Joint Strike Fighter single-engine design also made by Lockheed.

“I’m saying we know the J-20 is pretty much mirroring our F-22,” Manchin said. “We know that their J-31 is pretty much mirroring our F-35. We we know this and the cost to the American taxpayers … why wouldn’t we take hard actions against them? I just don’t understand why we wouldn’t retaliate from a financial standpoint.”

Deputy Defense Secretary Bob Work acknowledged that the Chinese “have stolen information from our defense contractors and it has helped them develop systems.” But he said, “we have hardened our systems.”

As part of the plea deal, Su admitted to working with two people from China from October 2008 to March 2014 to gain unauthorized access to computers belonging to Boeing Co. in Orange County, California, to steal sensitive military information and illegally export it to China, according to the the Justice Department release.

Here’s how they did it, according to the document:

“As part of the conspiracy, Su would e-mail the co-conspirators with guidance regarding what persons, companies and technologies to target during their computer intrusions. One of Su’s co-conspirators would then gain access to information residing on computers of U.S. companies and email Su directory file listings and folders showing the data that the co-conspirator had been able to access. Su then directed his co-conspirator as to which files and folders his co-conspirator should steal. Once the co-conspirator stole the data, including by using techniques to avoid detection when hacking the victim computers, Su translated the contents of certain stolen data from English into Chinese. In addition, Su and his co-conspirators each wrote, revised and emailed reports about the information and technology they had acquired by their hacking activities, including its value, to the final beneficiaries of their hacking activities.”

Su was arrested in Canada in July 2014, waived extradition and consented to be extradited to the U.S. in February, the release states. He faces a maximum sentence of five years in prison and a fine of $250,000 or twice the amount he gained from the offense, whichever is greatest, it states. He is scheduled to be sentenced on July 13, it states.